Cleveland, OH--For 20 years, Jim Jatich was completely dependent on others for everything, eating, shaving, combing his hair. Today, he talks on the phone, works on a computer, pours his own drinks thanks to Functional Electronic Stimulation (FES).
The Freehand, a FES device developed at Cleveland FES Center and offered commercially by NeuroControl, gives a person the ability to use either a lateral or palmer grasp via a shoulder control system.
"The real challenge engineering-wise was to move this device from prototype to mass production for commercial use," says Geoffrey Thrope, vice president of NeuroControl.
For the clinical trials, NeuroControl developed a standardized data collection system that proved the patient had no finger control prior to surgery, with improvement after. First, NeuroControl engineers measured the force of pinch. Starting with a standard force transducer used to measure the strength of a pinch in normal hands, engineers modified the instrument for a paralyzed hand. "It took months to figure out how to keep a patient's finger in place long enough to take a measurement," Thrope says. "Finally, we hit on the idea to use aluminum rods shaped in an L bracket. We coated the surface with the same rubber material used for Ping-Pong paddle faces."
Next, engineers developed a standing object manipulation task test. A physical therapist came up with six representative tasks that a patient would not be able to do without a hand system. One such test was the "baked potato" standard. Researchers gauged the force exerted by a person to break the surface of a baked potato with a fork using a normal force transducer. The average force became the standard. Next, NeuroControl placed a plunger in a hollow cylinder. Underneath the plunger was a spring with a constant that matched the calculated standard. The patient was required to grasp the plunger and push its Teflon rod to that level.
Another challenge was programming software for the electrical implant. With a specially written, Windows-based software program, therapists could program and customize the system to each patient's needs without an engineer present.
FDA approved the Freehand last August for adults with quadriplegia with C5 or C6 (fifth or sixth cervical vertebrae) spinal cord injuries.
In the U.S., 16 clinical centers are trained to implant the device. Ninety patients are now using it. Out of the 200,000 people in the U.S. with spinal cord injuries, 25,000 of these could be evaluated to use the Freehand system.